Top Power BI Interview Questions with Answers
1️⃣ What is Power BI?
Power BI is a business analytics tool by Microsoft that allows users to visualize data, build interactive reports, and gain insights. It connects to various data sources, transforms raw data, and helps in decision-making through real-time dashboards and reports.
2️⃣ Difference between Power BI Desktop and Power BI Service
Power BI Desktop: A Windows application used for building and designing reports. It allows data import, modeling, and creating visuals.
Power BI Service: A cloud-based platform where reports/dashboards can be published, shared, and accessed online. It supports collaboration, scheduled refresh, and sharing.
3️⃣ What are the main components of Power BI?
- Power BI Desktop – For report development
- Power BI Service – Online sharing and collaboration
- Power BI Mobile – Mobile access to reports
- Power Query – Data transformation
- Power Pivot – Data modeling
- Power View – Data visualization
- Power Map – Geo-spatial visualization
4️⃣ What is Power Query?
Power Query is a data connection and transformation tool used in Power BI to import, clean, and reshape data from various sources before loading it into the model. It uses the M language and provides a no-code editor for ETL operations.
5️⃣ What is DAX in Power BI?
DAX (Data Analysis Expressions) is a formula language used in Power BI for creating custom calculations, measures, and calculated columns. It is essential for data modeling and creating business logic inside the report.
6️⃣ What are measures and calculated columns?
Measures: Calculations evaluated at query time (e.g., SUM of sales). Created using DAX. Used in visuals.
Calculated Columns: New data columns added to tables. Evaluated during data load or refresh. Used for data transformation.
7️⃣ How do you create relationships between tables?
Relationships are created in the Model view by dragging one column (usually a key) to a matching column in another table. You can also define them manually by selecting:
- Primary foreign keys
- Cardinality (One-to-One, One-to-Many)
- Cross-filter direction (Single/Both)
8️⃣ What is a data model?
A data model is the structured combination of tables, relationships, and business logic (DAX measures, calculated columns) within Power BI that defines how data is stored, connected, and queried for reporting.
9️⃣ What are slicers in Power BI?
Slicers are visual filters in Power BI reports that allow users to select values and dynamically filter other visuals. They provide an intuitive way to control which data is displayed (e.g., filter by year or region).
🔟 Difference between slicers and filters
Slicers: Visual elements placed on reports; end-users can interact with them. Visible on the report page.
Filters: Applied in the filter pane (visual-level, page-level, report-level); not always visible to users.